The present invention relates to a rubber composition for a tread and a tire comprising thereof.
A rubber composition compounded with 100% by weight of a natural rubber has been conventionally used as a rubber composition for producing the tread of a tire (rubber composition for a tread). However, in this case, since the grip force of the obtained tire is low, the grip force was controlled to be improved by further mixing a rubber component comprising petroleum resources such as a styrene-butadiene rubber together with the natural rubber as the rubber component.
However, in the recent years, the regulation for CO2 discharge has become tighter as environmental problems have been considered more, and the limited crude petroleum supply has been decreasing year by year. Thus, the inflation of oil price in the future is predicted, and there is a limitation in using materials, such as a styrene-butadiene rubber and carbon black, made of petroleum resources. Accordingly, assuming the depletion of petroleum in future, it is necessary to use resources other than petroleum such as a natural rubber and white fillers such as silica and calcium carbonate. However, in that case, there are required performances which are the same as or more of tread performance (for example, the grip performance of a tire) and the hardness and processability of a rubber composition for a tread which are obtained by using petroleum resources conventionally used.
In order to improve the fore-mentioned performances using resources other than petroleum, for example, a method for producing a rubber composition for a tread which contains an epoxidized natural rubber being a resource other than petroleum as a rubber component is disclosed in Japanese Unexamined Patent Publication No. 2002-533234. However, since BET specific surface area of silica compounded in the rubber composition is large, processability at production of tires was inferior.